Acardia is a bizarre fetal malformation occurring only in twins or triplets. It is also called acardius acephalus, acardiac twinning, or twin reversed arterial perfusion (TRAP) syndrome or sequence. This condition is very rare and occurs in 1 in 34,600 births or 1 in 100 monozygotic twins (Gillim and Hendricks 1953) and 1 in 30 monozygotic triplets (Van Allen et al. 1983; Napolitani and Schreiber 1960; Moore et al. 1990; Sanjaghsaz et al. 1998; Blenc et al. 1999) and even in quintuplets. Almost all cases reported are monozygotic twins. However, there are reports of dichorionic monozygotic twin gestations with TRAP sequence (French et al. 1998; Gewolb et al. 1983).
- Bornstein, E., Monteagudo, A., Dong, R., et al. (2008). Detection of twin reversed arterial perfusion sequence at the time of first-trimester screening: The added value of 3-dimensional volume and color Doppler sonography. Journal of Ultrasound in Medicine, 27, 1105–1109.CrossRefPubMedGoogle Scholar
- Chen, H., Gonzalez, E., Hand, A. M., & Cuestas, R. (1983). The acardius acephalus and monozygotic twinning. Schumpert Medical Quarterly, 1, 195–199.Google Scholar
- Gillim, D. L., & Hendricks, C. H. (1953). Holoacardius: Review of the literature and case report. The Obstetrician and Gynaecologist, 2, 647–652.Google Scholar
- Martins, C. F., Santos, A. V., Miranda, M., et al. (2014). Twin reversed arterial perfusion (TRAP) sequence: An acardiac fetus. BMJ Case Reports, 11, 1–2.Google Scholar
- Sherer, D. M., Armstrong, B., Shah, Y. G., et al. (1989). Prenatal sonographic diagnosis. Doppler velocimetric umbilical cord studies and subsequent management of an acardiac twin pregnancy. The Obstetrician and Gynaecologist, 74, 472–475.Google Scholar